Projection objective with variable focal length

Claim 2

A projection objective with variable focal length, having a front member (F) with negative refractive power and a multiple-lens basic objective (G) with positive refractive power, with a multiple-lens variator (V) displaceable in the direction of the optical axis and with positive refractive power being arranged therebetween, whereof the middle lens has a negative refractive power, characterized by seven self-contained lenses (L1-L7) separated from each other by air spaces and free of cemented surfaces, whereof the front member (F) consists of one single lens (L1) with negative refractive power, the basic objective (G) consists of a Cookes or Taylor lens (L5, L6, L7) and the variator (V) likewise consists of a Cookes or Taylor lens (L2, L3, L4); the improvement comprising: that said variator includes means providing that its three lenses are maintained as a unit in fixed, spaced apart relationship to each other; and that said variator as said unit is adapted to be displaced along the optical axis between a position adjacent said front member (F) and a position adjacent said basic objective (G).

Claim 3

A projection objective according to claim 1, characterized by the following construction data of an objective with a focal length range of 70-120 mm and a focal length alteration of 1:1.714 and an aperture ratio of essentially 1:3.4: ______________________________________ n.sub.d ν.sub.d ______________________________________ r.sub.1 -141.250 L1 d.sub.1 = 2.000 1.487 70.41 r.sub.2 262.270 l.sub.1 = 51.000 to 2.139 r.sub.3 53.858 L2 d.sub.2 = 3.500 1.713 53.83 r.sub.4 205.350 l.sub.2 = 7.000 r.sub.5 57.876 L3 d.sub.3 = 9.600 1.805 25.43 r.sub.6 32.313 l.sub.3 = 1.105 r.sub.7 45.643 L4 d.sub.4 = 3.200 1.713 53.83 r.sub.8 117.150 l.sub.4 = 0.700 to 49.561 r.sub.9 24.582 L5 d.sub.5 = 7.600 1.744 54.77 r.sub.10 34.227 l.sub.5 = 1.837 r.sub.11 -658.790 L6 d.sub.6 = 1.200 1.773 32.21 r.sub.12 26.799 l.sub.6 = 6.400 r.sub.13 81.752 L7 d.sub.7 = 3.500 1.744 54.77 r.sub.14 -81.752 ______________________________________ wherein r represents the radii of curvature of the individual lenses, d their axial thicknesses, 1 the air spaces between the lenses, nd the indices of refraction and ν the abbe's coefficients of the lenses.

Claim 4

A projection objective according to claim 1, characterized by the following construction data of an objective with a focal length range of 85-145 mm and a focal length alteration of 1:1.706 and an aperture ratio of essentially 1:4: ______________________________________ n.sub.d ν.sub.d ______________________________________ r.sub.1 -149.620 L1 d.sub.1 = 2.000 1.487 70.41 r.sub.2 237.140 l.sub.2 = 51.000 to 2.140 r.sub.3 53.858 L2 d.sub.3 = 3.500 1.713 53.83 r.sub.4 205.350 l.sub.4 = 7.000 r.sub.5 57.876 L3 d.sub.5 = 9.600 1.805 25.43 r.sub.6 32.313 l.sub.6 = 1.105 r.sub.7 45.643 L4 d.sub.7 =3.200 1.713 53.83 r.sub.8 117.150 l.sub.8 = 0.700 to 49.560 r.sub.9 22.876 L5 d.sub.9 = 6.000 1.744 54.77 r.sub.10 33.256 l.sub.10 = 1.289 r.sub.11 113.830 L6 d.sub.11 = 1.200 1.648 33.05 r.sub.12 22.549 l.sub.12 = 12.400 r.sub.13 73.388 L7 d.sub.13 = 3.000 1.744 54.77 r.sub.14 -570.490 ______________________________________ wherein r represents the radii of curvature of the individual lenses, d their axial thicknesses, 1 the air spaces between the lenses, nd the indices of refraction and ν the abbe's coefficient of the lenses.